Ammonia synthesis system comprising catalytic layer comprising microwave reactive catalyst mixture

Abstract

The present disclosure relates to an ammonia synthesis system comprising: an ammonia synthesis reactor; two or more catalyst layers included in the ammonia synthesis reactor; a backflow prevention plate disposed downstream of each of the catalyst layers other than the lowermost catalyst layer among the two or more catalyst layers, the backflow prevention plate preventing backflow of the mixed gas; a distribution device that is disposed upstream of each of the two or more catalyst layers and distributes a mixed gas to the catalyst layers; a mixed gas supply line arranged so as to supply a mixed gas to the distribution device; and a microwave heating device that irradiates microwaves to each of the two or more catalyst layers, in which the catalyst layers include a microwave reactive catalyst mixture that includes a catalyst and a carbon body.

Description

Technical Field

[0001] The present disclosure relates to an ammonia synthesis system including a catalytic layer containing a microwave-reactive catalyst mixture. Background Art

[0002] In order to address climate change and the depletion of oil resources for the purpose of reducing greenhouse gas emissions, the necessity of using new renewable energy is increasing. However, the regions that meet the appropriate conditions for producing new renewable energy are limited, so it is necessary to develop means for storage and transportation. For example, there is a problem of transporting the new renewable energy rich in the equatorial vicinity and southern hemisphere regions to the northern hemisphere where there is a high demand for new renewable energy.

[0003] In addition, new renewable energy has time variability, so an electricity storage device must be accompanied. To solve the problems caused by the regional bias and time variability of new renewable energy, ammonia has attracted much attention as an energy carrier. In particular, ammonia can be liquefied at normal temperature and 8.5 atmospheres, so it has the advantage of being easier to store and transport compared to hydrogen. Therefore, as an alternative to solve the problems caused by the regional bias and time variability of new renewable energy, it is necessary to pay attention to the scheme of using electricity produced from new renewable energy to produce hydrogen and nitrogen and synthesizing ammonia using the produced hydrogen and nitrogen as raw materials.

[0004] Hydrogen, as the main raw material in ammonia synthesis, can be produced in a water electrolyzer driven by new renewable energy such as solar energy or wind energy. New renewable energy such as solar energy or wind energy has time variability. For example, solar energy cannot be used at night. Therefore, the ammonia synthesis system can never operate at a constant flow rate, and there is a problem of needing to predict and handle the flow rate fluctuations occurring during the production cycle.

[0005] In addition, when the flow rate of a raw material such as hydrogen introduced into the ammonia synthesis system decreases, there is a problem that the non-uniformity of the flow rate distribution increases at the front end of the catalytic layer included in the ammonia synthesis reactor.

[0006] Moreover, in the existing ammonia synthesis system, especially in the initial stage of operation, a temperature deviation occurs between the central part and the edge part of the catalytic layer, resulting in a problem of reducing the ammonia synthesis yield.

[0007] For this reason, it is necessary to develop an ammonia synthesis system that can cope with the flow rate fluctuations occurring during the production cycle, and at the same time, can solve the non-uniformity of the flow rate distribution occurring at the front end of the catalytic layer and the problem of reducing the ammonia synthesis yield due to the temperature deviation between the central part and the edge part of the catalytic layer in the initial stage of operation.

[0008] In addition, it is necessary to develop a substance with excellent microwave reactivity when microwaves are irradiated onto the catalytic layer of the ammonia synthesis system. SUMMARY OF THE INVENTION

[0009] According to one aspect of the present disclosure, an ammonia synthesis system capable of coping with flow rate fluctuations occurring during the production cycle can be provided.

[0010] According to another aspect of the present disclosure, an ammonia synthesis system can be provided that can maintain a uniform flow rate distribution at the front end of the catalyst layer included in the ammonia synthesis reactor even when the flow rate of raw materials such as hydrogen introduced is reduced.

[0011] According to still another aspect of the present disclosure, an ammonia synthesis system can be provided that can make the temperature deviation between the central portion and the edge portion of the catalyst layer uniform at the initial stage of operation, thereby improving the ammonia synthesis yield.

[0012] According to one aspect of the present disclosure, an ammonia synthesis system can be provided that preheats the catalyst layer at the initial stage of operation, thereby improving the ammonia synthesis yield at the initial stage of operation.

[0013] According to one aspect of the present disclosure, an ammonia synthesis system can be provided that optimizes the amount of energy required in the system during operation, thereby saving energy.

[0014] According to one aspect of the present disclosure, an ammonia synthesis system can be provided that uniformly uses each catalyst layer during operation, thereby extending the catalyst replacement cycle.

[0015] According to another aspect of the present disclosure, a catalyst mixture excellent in microwave reactivity during ammonia synthesis can be provided.

[0016] According to another aspect of the present disclosure, a catalyst mixture can be provided that can improve the heating characteristics and ammonia synthesis yield of the catalyst mixture when irradiated with microwaves.

[0017] The present disclosure provides an ammonia synthesis system including: an ammonia synthesis reactor; two or more catalyst layers included in the ammonia synthesis reactor; a backflow prevention plate disposed downstream of each of the catalyst layers other than the lowermost catalyst layer among the two or more catalyst layers to prevent backflow of the mixed gas; a distribution device disposed upstream of each of the two or more catalyst layers to distribute the mixed gas to the catalyst layer; a mixed gas supply line arranged to supply the mixed gas to the distribution device; and a microwave heating device that irradiates microwaves to each of the two or more catalyst layers. In the ammonia synthesis system, the catalyst layer includes a microwave-reactive catalyst mixture, and the microwave-reactive catalyst mixture includes a catalyst and a carbon body.

[0018] According to an embodiment of the present disclosure, the microwave-reactive catalyst mixture may be formed by mixing the catalyst and the carbon body.

[0019] According to an embodiment of the present disclosure, the microwave reactive catalyst mixture may be in the form of pellets or granules.

[0020] According to an embodiment of the present disclosure, the microwave reactive catalyst mixture may contain the catalyst and the carbon body in a weight ratio of 0.5:1 to 10:1.

[0021] According to an embodiment of the present disclosure, the carbon body may include at least one selected from the group consisting of carbon nanotubes, fullerenes, graphite, graphene, carbon black, Ketjen black, and carbon fibers.

[0022] According to an embodiment of the present disclosure, the catalyst may include at least one selected from the group consisting of ruthenium (Ru) and cesium (Cs) as a catalyst active ingredient, and may include at least one selected from the group consisting of cerium oxide, lanthanum oxide, vanadium oxide, magnesium oxide, aluminum oxide, zirconium oxide, tungsten oxide, and titanium oxide as a catalyst support.

[0023] According to an embodiment of the present disclosure, the microwave reactive catalyst mixture may further include silicon carbide (SiC).

[0024] According to an embodiment of the present disclosure, the ammonia synthesis system may further include: a distribution plate respectively located between the catalytic layer and the distribution device.

[0025] According to an embodiment of the present disclosure, the ammonia synthesis system may further include: a plurality of mixed gas flow tubes fixed to the lower surface of the distribution plate for the mixed gas to flow through.

[0026] According to an embodiment of the present disclosure, the mixed gas flow tube has a bottom surface and a side surface connecting the bottom surface and the distribution plate. A plurality of upper openings are formed at intervals along the perimeter on the upper side surface of the mixed gas flow tube, a plurality of middle openings are formed at intervals along the perimeter on the middle side surface of the mixed gas flow tube, and a plurality of lower openings are formed at intervals along the perimeter on the lower side surface of the mixed gas flow tube. The mixed gas flow tube includes a cover member formed to surround at least a partial area of the side surface of the mixed gas flow tube to provide a space for guiding the fluid flowing out of the side surface of the mixed gas flow tube after passing through the upper openings to the middle opening side.

[0027] According to an embodiment of the present disclosure, the mixed gas flow tube may further include: a partition configured to divide the upper part and the middle part of the mixed gas flow tube.

[0028] According to an embodiment of the present disclosure, it may be that each of the mixed gas supply routes includes a flow regulating device.

[0029] According to an embodiment of the present disclosure, it may be that a plurality of openings are formed on each of the backflow prevention plates, and a backflow prevention cover that selectively opens in the gas flow direction is formed in the plurality of openings formed on each of the backflow prevention plates.

[0030] According to an embodiment of the present disclosure, it may be that the backflow prevention cover is hinge-coupled to a position on the circumference of the plurality of openings formed on each of the backflow prevention plates.

[0031] According to an embodiment of the present disclosure, it may be that a spring is provided at the hinge coupling portion of the hinge coupling, so as to apply an elastic force in the direction in which the backflow prevention cover approaches the distribution plate.

[0032] According to an embodiment of the present disclosure, it may be that the distribution device is in the shape of a circular plate or toroidal.

[0033] According to an embodiment of the present disclosure, it may be that in the ammonia synthesis system, ammonia synthesis is carried out at 1 to 300 bar.

[0034] According to an embodiment of the present disclosure, it may be that in the ammonia synthesis system, ammonia synthesis is carried out at 200 to 700 °C.

[0035] According to an embodiment of the present disclosure, it may be that the ammonia synthesis system further includes: a heat exchanger, which is arranged downstream of each of the two or more catalyst layers, and removes heat from the effluent of the catalyst layer.

[0036] The ammonia synthesis system according to an embodiment of the present disclosure can cope with flow rate fluctuations occurring during the production cycle.

[0037] The ammonia synthesis system according to another embodiment of the present disclosure can maintain a uniform flow distribution at the front end of the catalyst layer included in the ammonia synthesis reactor even when the flow rate of raw materials such as hydrogen introduced is reduced.

[0038] The ammonia synthesis system according to still another embodiment of the present disclosure makes the temperature deviation between the central portion and the edge portion of the catalyst layer uniform in the initial stage of operation, thereby enabling an increase in the ammonia synthesis yield.

[0039] The ammonia synthesis system according to an embodiment of the present disclosure preheats the catalyst layer in the initial stage of operation, thereby enabling an increase in the ammonia synthesis yield in the initial stage of operation.

[0040] The ammonia synthesis system according to an embodiment of the present disclosure optimizes the amount of energy required in the system during operation, thereby enabling energy savings.

[0041] The ammonia synthesis system according to an embodiment of the present disclosure, during operation, evenly uses each catalytic layer, thereby being able to extend the replacement cycle of the catalyst.

[0042] The ammonia synthesis system according to an embodiment of the present disclosure can provide a catalyst mixture with excellent microwave reactivity during ammonia synthesis.

[0043] The ammonia synthesis system according to an embodiment of the present disclosure can provide a catalyst mixture that can improve the heating characteristics and ammonia synthesis yield of the catalyst mixture when irradiating microwaves.

[0044] The ammonia synthesis system according to an embodiment of the present disclosure can synthesize ammonia in an eco-friendly manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 FIG. is a schematic diagram showing an ammonia synthesis system according to an embodiment of the present disclosure.

[0046] Figure 2 FIG. is a schematic diagram showing an ammonia synthesis system according to an embodiment of the present disclosure.

[0047] Figure 3 FIG. is a perspective view showing a distribution plate and a mixed gas flow tube according to an embodiment of the present disclosure.

[0048] Figure 4 FIG. is a perspective view showing the inside of a mixed gas flow tube according to an embodiment of the present disclosure.

[0049] Figure 5 FIG. is a perspective view showing the inside of a mixed gas flow tube according to another embodiment of the present disclosure.

[0050] Figure 6 FIG. is a view showing a state in which a backflow prevention cover is closed in a backflow prevention plate according to an embodiment of the present disclosure.

[0051] Figure 7 FIG. is a view showing a state in which a backflow prevention cover is opened in a backflow prevention plate according to an embodiment of the present disclosure.

[0052] Reference Numerals: 1: ammonia synthesis system; 10: ammonia synthesis reactor; 20, 21: catalyst layer; 30, 31: backflow prevention plate; 301: backflow prevention plate; 302: opening; 303: backflow prevention cover; 304: hinge; 40, 41: distribution device; 50, 51: mixed gas supply line; 60, 61: microwave heating device; 601, 602: microwave guiding part; 70, 71: distribution plate; 72: lower surface; 720: mixed gas flow pipe; 722: side surface; 722a: upper part; 722b: middle part; 722c: lower part; 723: upper opening; 725: middle opening; 727: lower opening; 729: partition; 730: covering member. Detailed Description of the Invention

[0053] The advantages, features, and methods for achieving the same of the present invention will become clear through the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below and can be implemented in various different forms. These embodiments are only provided to make the disclosure of the present invention complete and to fully inform those with ordinary knowledge in the technical field to which the present invention pertains of the scope of the invention. The present invention is only defined by the scope of the claims.

[0054] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this specification have the same meaning as those commonly understood by those skilled in the technical field to which this disclosure pertains.

[0055] Unless otherwise stated in the context, the singular forms used in this specification may also include the plural forms.

[0056] The numerical ranges used in this specification include all values within the range including the lower limit value and the upper limit value, increments logically derived from the form and span of the defined range, all values with double limits, and all possible combinations of the upper and lower limits within the numerically defined range in different forms. Unless otherwise defined in the specification of the present invention, values that may exceed the numerical range due to experimental errors or rounding of numerical values are also included in the defined numerical range.

[0057] The term "comprising" mentioned in this specification is an open-ended description and is equivalent in meaning to expressions such as "having", "containing", "possessing", "having the characteristics", etc., and does not exclude factors, materials, or processes not additionally listed.

[0058] Unless otherwise defined, the unit "%" not specifically mentioned as used in this specification represents "% by weight".

[0059] Unless otherwise defined, "A to B" in this specification means "A or more and B or less".

[0060] In this specification, "microwave reactivity" refers to the property that when microwaves are irradiated, the heating rate of the temperature of the catalyst layer increases, or the ammonia synthesis rate increases, or both the heating rate of the temperature of the catalyst layer and the ammonia synthesis rate increase.

[0061] Hereinafter, the ammonia synthesis system of the present disclosure will be described in detail. However, it is merely an example, and the present disclosure is not limited to the specific embodiments described by the example.

[0062] The present disclosure provides an ammonia synthesis system, which includes: an ammonia synthesis reactor; two or more catalyst layers included in the ammonia synthesis reactor; a backflow prevention plate disposed downstream of each of the catalyst layers other than the lowermost catalyst layer among the two or more catalyst layers to prevent backflow of the mixed gas; a distribution device disposed upstream of each of the two or more catalyst layers to distribute the mixed gas to the catalyst layers; a mixed gas supply line arranged to supply the mixed gas to the distribution device; and a microwave heating device that irradiates microwaves to each of the two or more catalyst layers. Among them, the catalyst layer includes a microwave-reactive catalyst mixture, and the microwave-reactive catalyst mixture includes a catalyst and a carbon body.

[0063] The ammonia synthesis system of the present disclosure can provide a catalyst mixture with excellent microwave reactivity during ammonia synthesis. In addition, the ammonia synthesis system of the present disclosure can provide a catalyst mixture that can improve the ammonia synthesis yield when microwaves are irradiated.

[0064] Compared with the existing heating methods that heat the catalyst by conduction or convection, microwaves selectively heat the active sites on the surface of the catalyst. The selective heating of microwaves can significantly reduce various reaction conditions such as temperature, pressure, time, and activation energy. In addition, the carbon body has π electrons in the sp2 hybridized carbon network, and the existence of such free electrons helps the carbon body to absorb microwave energy and be effectively heated. That is, during ammonia synthesis, by irradiating microwaves to the catalyst layer including the microwave-reactive catalyst mixture containing a catalyst and a carbon body, not only can the time for preheating the catalyst layer be shortened, but also the ammonia synthesis yield can be improved.

[0065] According to an embodiment of the present disclosure, the microwave-reactive catalyst mixture may be formed by mixing a catalyst and a carbon body. When the microwave-reactive catalyst mixture is mechanically mixed by a catalyst and a carbon body, the heating characteristics and ammonia production yield can be improved. This excellent effect can be attributed to the improvement of genetic characteristics. In addition, due to the synergistic effect of the catalyst and the carbon body, the interfacial polarization increases at the interface of the mixed catalyst, and the overall heating characteristics and ammonia production rate can be improved.

[0066] According to an embodiment of the present disclosure, the microwave-reactive catalyst mixture may be mechanically mixed by a catalyst and a carbon body. Additionally, the microwave-reactive catalyst mixture may also be synthesized by co-precipitation or hydrothermal reaction of a catalyst and a carbon body, etc., but is not limited thereto.

[0067] The microwave-reactive catalyst mixture may have different weights in each layer of the catalytic layer. For example, when assuming that the catalytic layer has three layers, it may contain the microwave-reactive catalyst mixture in a greater weight in the middle catalytic layer than in the uppermost catalytic layer, and may contain the microwave-reactive catalyst mixture in a greater weight in the lowermost catalytic layer than in the middle catalytic layer. However, this is only an example, and the weight of the microwave-reactive catalyst mixture included in each catalytic layer may be different according to the reaction conditions and operating conditions. The weight of the microwave-reactive catalyst mixture included in each catalytic layer may also be different according to the configuration form or number of the microwave heating device.

[0068] According to an embodiment of the present disclosure, the microwave-reactive catalyst mixture may be in the form of pellets or granules, but is not limited thereto, and may also be included in the catalytic layer in other different forms.

[0069] According to an embodiment of the present disclosure, the microwave-reactive catalyst mixture may contain a catalyst and a carbon body in a weight ratio of 0.1:1 to 50:1, 0.5:1 to 10:1, or 1:1 to 5:1, but is not limited thereto.

[0070] Additionally, in one catalytic layer, the weight ratio of the catalyst and the carbon body of the microwave-reactive catalyst mixture is not fixed, and may also be different in the directions away from the center of the catalytic layer up, down, left, and right. For example, the weight ratio may also be made different by gradually containing more catalyst relative to the carbon body in the directions away from the center of the catalytic layer to the left and right, or by gradually containing more carbon body relative to the catalyst in the directions away from the center of the catalytic layer to the left and right. However, this is only an example, and the weight ratio of the microwave-reactive catalyst mixture may be different in the directions away from the center of the catalytic layer according to the reaction conditions and operating conditions. The weight ratio of the microwave-reactive catalyst mixture may also be different according to the configuration form or number of the microwave heating device.

[0071] According to an embodiment of the present disclosure, the carbon body may include at least one selected from the group consisting of carbon nanotubes, fullerenes, graphite, graphene, carbon black, Ketjen black, and carbon fibers, but is not limited thereto. Specifically, the carbon body may be a carbon nanotube. The carbon body has π electrons in the sp2 hybridized carbon network, and the presence of such free electrons helps the carbon body to absorb microwave energy and heat effectively. That is, during ammonia synthesis, by irradiating microwaves to the catalytic layer including the microwave-reactive catalyst mixture containing the catalyst and the carbon body, not only can the time for preheating the catalytic layer be shortened, but also the ammonia synthesis yield can be increased.

[0072] According to an embodiment of the present disclosure, the catalyst may include at least one selected from the group consisting of ruthenium (Ru) and cesium (Cs) as a catalyst active ingredient.

[0073] According to an embodiment of the present disclosure, the catalyst may include at least one selected from the group consisting of cerium oxide, lanthanum oxide, vanadium oxide, magnesium oxide, aluminum oxide, zirconium oxide, tungsten oxide, and titanium oxide as a catalyst support, but is not limited thereto. Specifically, the catalytic layer may include cerium oxide as a catalyst support.

[0074] Specifically, the catalyst may include at least one selected from the group consisting of ruthenium (Ru) and cesium (Cs) as a catalyst active ingredient and may include cerium oxide as a catalyst support. When the catalyst is configured as above, in particular, it exhibits excellent microwave reactivity characteristics.

[0075] According to an embodiment of the present disclosure, the microwave-reactive catalyst mixture may further include silicon carbide (SiC). The microwave-reactive catalyst mixture further includes silicon carbide, thereby enabling improvement of microwave reactivity. That is, under the irradiation of microwaves, the heating characteristics can be improved, and the ammonia production yield can be further increased. Silicon carbide is further included in the microwave-reactive catalyst mixture, thereby enabling it to be located in the catalytic layer and provided to cover the outside of the reactor, and thus can also be used for heating when microwaves are irradiated.

[0076] Reference Figure 1 and Figure 2, according to an embodiment of the present disclosure, an ammonia synthesis system 1 can be provided, which includes: an ammonia synthesis reactor 10; two or more catalytic layers 20, 21, which are included in the ammonia synthesis reactor 10; anti-backflow plates 30, 31, which are arranged downstream of each of the catalytic layers other than the lowermost catalytic layer among the two or more catalytic layers 20, 21 to prevent the mixed gas from flowing back; distribution devices 40, 41, which are arranged upstream of each of the two or more catalytic layers 20, 21 to distribute the mixed gas to the catalytic layers 20, 21; mixed gas supply routes 50, 51, which are arranged to supply the mixed gas to the distribution devices 40, 41; and microwave heating devices 60, 61, which irradiate microwaves to each of the two or more catalytic layers 20, 21 respectively.

[0077] Hereinafter, as an example of the ammonia synthesis system 1 of the present disclosure, an ammonia synthesis system including two catalytic layers can be described. Of course, ammonia synthesis systems including two or more, for example, three, four, five, seven, or ten catalytic layers are included in an embodiment of the present disclosure.

[0078] The ammonia synthesis system according to an embodiment of the present disclosure includes a mixed gas supply route to supply the mixed gas to each of the two or more catalytic layers respectively, so as to be able to cope with the flow rate changes occurring during the production cycle. For example, when the flow rate of the input raw material is high, it can be input through the upper mixed gas supply route 50 to pass through from the uppermost catalytic layer 20, and when the flow rate of the input raw material is low, it can be input through the lower mixed gas supply route 51 to pass through the lower catalytic layer 21 instead of the upper catalytic layer 20, and thus operate. At this time, when the mixed gas is input through the lower mixed gas supply route 51 to pass through the lower catalytic layer 21, the anti-backflow plate 30 is used to prevent the mixed gas from flowing back.

[0079] At this time, for convenience, in this specification, the situations of flow rate changes occurring during the production cycle are roughly divided into three types. As described above, they can be divided into the situation of low flow rate, the situation of normal flow rate, and the situation of high flow rate, and can be easily adjusted according to the common sense or judgment of those skilled in the art. It can be that the situation of low flow rate refers to the situation where it is less than half (50%) of the annual average production flow rate (100%), the situation of normal flow rate refers to the situation where it is more than half (50%) and less than or equal to twice (200%) of the annual average production flow rate (100%), and the situation of high flow rate refers to the situation where it exceeds twice (200%) of the annual average production flow rate (100%), but it is not limited thereto.

[0080] On the one hand, in the case where the flow rate of the ammonia synthesis system is small as described above, the mixed gas can be fed through the mixed gas supply line 51 located at the lower end to operate through the catalyst layer 21 located at the lower end, so there is no need to maintain the temperature of the entire reactor. Therefore, during operation, the amount of energy required in the system can be optimized as needed, thus saving energy.

[0081] In addition, during operation of the ammonia synthesis system, each catalyst layer is uniformly used, so that the replacement cycle of the catalyst or the catalyst mixture can be extended. Generally, when the flow rate of the reaction fluid is small, the distribution performance at the upper part of the catalyst layer decreases, resulting in differences in reaction performance among the catalysts at the same height. The replacement cycle of the catalyst is determined according to the reaction performance at the lower end of the catalyst layer. When the distribution performance decreases due to a decrease in flow rate, resulting in a decrease in reaction performance in some catalyst layer regions at the lower end, there is a problem of shortening the replacement cycle. However, as described in the ammonia synthesis system according to the present disclosure, as long as the height of the catalyst layer is set differently according to the flow rate and the distribution performance in each catalyst layer is improved, the catalyst layer can be used relatively uniformly, thereby extending the replacement cycle of the catalyst.

[0082] In addition, in the ammonia synthesis system according to an embodiment of the present disclosure, by including the microwave heating devices 60 and 61, the temperature deviation between the central part and the edge part of the catalyst layer can be made uniform at the initial stage of operation, thereby improving the ammonia synthesis yield. Specifically, the microwave heating device can make the temperature deviation between the central part and the edge part of the catalyst layer uniform by irradiating microwaves to the catalyst layer at the initial stage of operation. Moreover, the microwave heating device preheats the catalyst layer that is not sufficiently preheated at the initial stage of operation, thereby being able to improve the ammonia synthesis yield at the initial stage of operation.

[0083] For example, when the flow rate of the fed raw material is small, it can be operated to pass through the catalyst layer 21 located at the lower end instead of the catalyst layer 20 located at the upper end. At this time, the mixed gas is not fed to the catalyst layer 20 located at the upper end, so the temperature of the catalyst layer 20 located at the upper end will decrease over time. Then, when the catalyst layer 20 located at the upper end is used again, since the catalyst layer 20 located at the upper end is in a cooled state, the ammonia synthesis efficiency may decrease. At this time, the microwave heating device is used to irradiate microwaves to the catalyst layer 20 located at the upper end in the cooled state for preheating, so that excellent ammonia synthesis efficiency can be achieved even when the catalyst layer is reused for operation.

[0084] The catalyst layer may include a microwave-reactive catalyst mixture containing a catalyst and a carbon body. In this case, when microwaves are irradiated, the microwave-reactive catalyst mixture acts to more effectively absorb microwaves, thereby not only being able to shorten the time for preheating the catalyst layer, but also improving the ammonia synthesis yield.

[0085] The microwave heating device can be provided with more than 1, more than 2, more than 3, more than 4, more than 5 or more than 8, but not limited to this, in each catalytic layer. The number of microwave heating devices can increase according to the size of the reactor, and the installation positions can be adjusted for effective microwave irradiation.

[0086] The ammonia synthesis system can also include microwave guiding parts 601 and 602. The microwave guiding parts 601 and 602 can enable the microwaves irradiated from the microwave heating device to reach the catalytic layer more effectively. Of course, the shape or installation position of the guiding part can be changed according to the microwave waveform.

[0087] In an embodiment according to the present disclosure, the number of catalytic layers can be more than 2, more than 3, more than 4, more than 5, more than 6, more than 7, more than 10, 20 or less, 10 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, or an interval value of these numerical values. The number of catalytic layers and the number of distribution devices can be the same.

[0088] In an embodiment according to the present disclosure, the mixed gas can include at least one selected from the group consisting of hydrogen and nitrogen.

[0089] Hydrogen can be produced in a device driven by newly renewable energy. Specifically, hydrogen can be produced in a water electrolyzer driven by newly renewable energy.

[0090] The newly renewable energy can include at least one selected from the group consisting of solar heat, sunlight, bioenergy, wind power, hydropower, geothermal energy, ocean energy and waste energy. The newly renewable energy has time variability. For example, solar energy cannot be used at night. Therefore, when hydrogen is produced in a device driven by newly renewable energy, the ammonia synthesis system cannot always operate at a constant flow rate. That is, due to the time variability of the newly renewable energy, an ammonia synthesis system capable of coping with the flow rate fluctuations occurring during the production cycle is required.

[0091] In addition, the mixed gas supplied in the mixed gas supply routes 50 and 51 can be a cold mixed gas. Therefore, the mixed gas supplied in the mixed gas supply routes 50 and 51 serves to cool the mixed gas and can also act as a means for cooling the mixed gas flowing in the ammonia synthesis system. For example, the cold mixed gas can be used as a cooling means for cooling the mixed gas introduced into the catalytic layer.

[0092] The ammonia synthesis system according to an embodiment of the present disclosure can also include distribution plates 70 and 71, which are respectively located between the catalytic layers 20 and 21 and the distribution devices 40 and 41.

[0093] In addition, an ammonia synthesis system according to an embodiment of the present disclosure may further include: a plurality of mixed gas flow tubes 720 fixed to the lower surfaces 72 of the distribution plates 70 and 71 for the mixed gas to flow through.

[0094] The ammonia synthesis system further includes a distribution plate and mixed gas flow tubes, so that even when the flow rate of a raw material such as hydrogen decreases, a uniform flow rate distribution can be maintained at the front end of the catalyst layer included in the ammonia synthesis reactor.

[0095] Reference Figure 3 and Figure 4 The mixed gas flow tube 720 may have a bottom surface and side surfaces 722 connecting the bottom surface and the distribution plate.

[0096] It may be that a plurality of upper openings 723 are formed at intervals along the circumference on the side surface 722a of the upper part of the mixed gas flow tube 720, a plurality of middle part openings 725 are formed at intervals along the circumference on the side surface 722b of the middle part of the mixed gas flow tube 720, and a plurality of lower openings 727 are formed at intervals along the circumference on the side surface 722c of the lower part of the mixed gas flow tube 720. The mixed gas flows through the upper openings 723, the middle part openings 725, and the lower openings 727. The mixed gas flow tube 720 may include a cover 730 formed to surround at least a partial area of the side surface of the mixed gas flow tube 720 to provide a space for guiding the fluid flowing out of the side surface of the mixed gas flow tube 720 after passing through the upper openings 723 to the side of the middle part openings 725. The cover 730 may be formed to surround at least one of the group consisting of the upper part and the middle part of the side surface of the mixed gas flow tube 720.

[0097] The cover 730 guides the fluid flowing out of the side surface of the mixed gas flow tube 720 after passing through the upper openings 723 to the side of the middle part openings 725. Thus, a flow that moves to the outside of the side surface of the mixed gas flow tube 720 and then moves back to the inside of the side surface is formed. Through the flow formed in this way, the mixing of the fluid is completed more smoothly.

[0098] Reference Figure 5, the mixed gas flow tube 720 may further include a partition plate 729 configured to divide the upper part and the middle part of the mixed gas flow tube 720. The partition plate 729 completely separates the upper part and the middle part of the mixed gas flow tube 720 to prevent fluid from moving. Therefore, the fluid flowing into the upper part of the mixed gas flow tube 720 does not directly descend to the middle part due to the partition plate 729, but flows out through the upper opening 723 into the space between the mixed gas flow tube 720 and the cover 730. After that, the fluid flows into the mixed gas flow tube through the middle opening 725 in the space, descends to the lower part, and flows out of the mixed gas flow tube 720 through the lower opening 727. As described above, by forming a flow that flows out of the mixed gas flow tube 720 and then flows back into the interior and then flows out again, the mixing of the fluid can be completed more smoothly, and a uniform flow distribution can be maintained at the front end of the catalyst layer.

[0099] In an embodiment according to the present disclosure, each of the mixed gas supply routes 50, 51 may include a flow regulating device. The flow regulating device can independently control the flow rate of the mixed gas in each of the mixed gas supply routes. Specifically, the flow regulating device independently adjusts the flow rate of the mixed gas flowing in each of the mixed gas supply routes so that the flow rate of the mixed gas entering the distribution device remains within a required flow rate range. The flow regulating device may be a flow control valve.

[0100] In an embodiment according to the present disclosure, each of the mixed gas supply routes 50, 51 may be a route branched from one main supply route. Additionally, each of the mixed gas supply routes 50, 51 may also be supplied from separate supply routes with at least one selected from the group consisting of nitrogen and hydrogen.

[0101] In an embodiment according to the present disclosure, a plurality of openings 302 may be formed in each of the anti-backflow plates 30, 31, and an anti-backflow cover 303 that selectively opens according to the gas flow direction is formed in the plurality of openings 302 formed in each of the anti-backflow plates 30, 31. The ammonia synthesis system according to the present disclosure includes the anti-backflow plates 30, 31 formed with the anti-backflow covers 303, so that even if the mixed gas is introduced through the lower mixed gas supply route 51 to pass through the lower catalyst layer 21, the backflow of the mixed gas can be prevented. Additionally, as described above, by implementing a system capable of preventing the backflow of the mixed gas, the amount of energy required in the system can be optimized as needed during operation, thereby saving energy, and each catalyst layer can be evenly used, thereby extending the replacement cycle of the catalyst.

[0102] Reference Figure 6 and Figure 7 , the anti-backflow cover 303 may be coupled to a position on the perimeter of the plurality of openings 302 formed in each of the anti-backflow plates 30, 31 through a hinge 304.Figure 7 The state where the backflow prevention cover 303 coupled by the hinge 304 is opened is shown. When the mixed gas flows from the upstream to the downstream of the backflow prevention plates 30 and 31, the backflow prevention cover 303 remains in the open state, so that the mixed gas flows normally. Figure 6 The state where the backflow prevention cover 303 coupled by the hinge 304 is closed is shown. When the mixed gas wants to flow from the downstream to the upstream of the backflow prevention plates 30 and 31, the backflow prevention cover 303 is closed due to the flow of the mixed gas flowing from the downstream to the upstream. Due to this principle, the backflow prevention plates 30 and 31 according to the present disclosure can prevent the mixed gas from flowing back.

[0103] In an embodiment according to the present disclosure, a spring is provided at the hinge 304 coupling portion coupled by the hinge 304, so that an elastic force can be applied in the direction in which the backflow prevention cover 303 approaches the distribution plate.

[0104] In an embodiment according to the present disclosure, the distribution devices 40 and 41 may be in a circular plate shape or a toroidal shape, but are not limited thereto, and common gas distribution devices can be used.

[0105] In an ammonia synthesis system according to an embodiment of the present disclosure, ammonia synthesis can be carried out at 1 to 500 bar or 10 to 300 bar.

[0106] In addition, in an ammonia synthesis system according to an embodiment of the present disclosure, ammonia synthesis can be carried out at 100 to 800 °C or 200 to 700 °C.

[0107] An ammonia synthesis system according to an embodiment of the present disclosure may further include: a heat exchanger, which is arranged downstream of each of two or more catalytic layers to remove heat from the effluent of the catalytic layer. The heat exchanger can be arranged to surround the catalytic layer or around it. The ammonia synthesis system according to the present disclosure further includes a heat exchanger, so that it can have an additional heat removal unit other than supplying a cooling mixed gas. Thus, the ammonia synthesis system can be operated flexibly.

[0108] The content described above is only an example of applying the principle of the present disclosure, and other structures may also be included without departing from the scope of the present disclosure.

Claims

1. An ammonia synthesis system, comprising: Ammonia synthesis reactor; Two or more catalytic layers, which are included in the ammonia synthesis reactor; an anti-backflow plate, which is arranged downstream of each of the catalyst layers other than the lowest catalyst layer among the two or more catalyst layers to prevent the mixed gas from backflowing; a distribution device, which is arranged upstream of each of the two or more catalyst layers and distributes the mixed gas to the catalyst layer; a mixed gas supply route arranged to supply the mixed gas to the distribution device; and A microwave heating device irradiates microwaves to the two or more catalyst layers respectively, wherein: The catalytic layer includes a microwave-reactive catalyst mixture, and the microwave-reactive catalyst mixture includes a catalyst and a carbon body.

2. The ammonia synthesis system according to claim 1, wherein: The microwave reactive catalyst mixture is formed by mixing the catalyst and the carbon body.

3. The ammonia synthesis system according to claim 1, wherein: The microwave reactive catalyst mixture is in the form of pellets or particles.

4. The ammonia synthesis system according to claim 1, wherein: The microwave reactive catalyst mixture contains the catalyst and the carbon body in a weight ratio of 0.5:1 to 10:

1.

5. The ammonia synthesis system according to claim 1, wherein: The carbon body includes at least one selected from the group consisting of carbon nanotubes, fullerenes, graphite, graphene, carbon black, Ketjen black, and carbon fibers.

6. The ammonia synthesis system according to claim 1, wherein: The catalyst includes at least one selected from the group consisting of ruthenium and cesium as a catalyst active component, and includes at least one selected from the group consisting of cerium oxide, lanthanum oxide, vanadium oxide, magnesium oxide, aluminum oxide, zirconium oxide, tungsten oxide and titanium oxide as a catalyst support.

7. The ammonia synthesis system according to claim 1, wherein: The microwave-reactive catalyst mixture also includes silicon carbide.

8. The ammonia synthesis system according to claim 1, wherein: The ammonia synthesis system further includes distribution plates respectively located between the catalytic layer and the distribution device.

9. The ammonia synthesis system according to claim 8, wherein: The ammonia synthesis system further includes: a plurality of mixed gas flow pipes fixed on the lower surface of the distribution plate for allowing the mixed gas to flow.

10. The ammonia synthesis system according to claim 9, wherein: The mixed gas flow pipe has a bottom surface and a side surface connecting the bottom surface and the distribution plate. A plurality of upper openings are formed on the upper side of the mixed gas flow pipe and are spaced apart along the circumference. A plurality of intermediate openings are formed on the intermediate side of the mixed gas flow pipe at intervals along the circumference. A plurality of lower openings are formed on the lower side of the mixed gas flow pipe and are spaced apart along the circumference. The mixed gas flow pipe includes a cover formed to surround at least a portion of a side surface of the mixed gas flow pipe to provide a space for guiding a fluid that flows out of the side surface of the mixed gas flow pipe after passing through the upper opening toward the middle opening.

11. The ammonia synthesis system according to claim 10, wherein: The mixed gas flow pipe further includes a partition plate configured to divide the upper portion and the middle portion of the mixed gas flow pipe.

12. The ammonia synthesis system according to claim 1, wherein: The mixed gas supply routes each include a flow regulating device.

13. The ammonia synthesis system according to claim 1, wherein: A plurality of openings are formed on each of the backflow prevention plates. A backflow prevention cover that is selectively opened according to a gas flow direction is formed at a plurality of openings formed on each of the backflow prevention plates.

14. The ammonia synthesis system according to claim 13, wherein: The backflow prevention cover is hingedly coupled to a position of a peripheral portion of a plurality of openings formed on each of the backflow prevention plates.

15. The ammonia synthesis system according to claim 14, wherein: A spring is provided at the hinge joint portion of the hinge joint, so as to apply elastic force to the direction in which the backflow prevention cover approaches the distribution plate.

16. The ammonia synthesis system according to claim 1, wherein: The distribution device is in the shape of a circular plate or a ring.

17. The ammonia synthesis system according to claim 1, wherein: In the ammonia synthesis system, ammonia synthesis is performed at 1 to 300 bar.

18. The ammonia synthesis system according to claim 1, wherein: In the ammonia synthesis system, ammonia synthesis is performed at 200 to 700°C.

19. The ammonia synthesis system according to claim 1, wherein: The ammonia synthesis system further includes a heat exchanger disposed downstream of each of the two or more catalyst layers to remove heat from an outflow of the catalyst layer.

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